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BUG: Reference leak in PyUFunc_GenericReduction on CheckOverride error #31677
Description
Bug Description
In numpy/_core/src/umath/ufunc_object.c, when PyUFunc_CheckOverride fails in PyUFunc_GenericReduction, the code returns NULL directly instead of jumping to the cleanup label, leaking full_args.in and full_args.out.
Location
numpy/_core/src/umath/ufunc_object.c:3777-3780
Code
int errval = PyUFunc_CheckOverride(ufunc, _reduce_type[operation],
full_args.in, full_args.out, wheremask_obj, args, len_args, kwnames, &override);
if (errval) {
return NULL; // BUG: should be `goto fail` — leaks full_args.in/out
}Impact
When reduce/accumulate/reduceat encounters a __array_ufunc__ override error, the full_args.in and full_args.out tuple references are leaked. This happens every time an override is attempted on an object that raises an exception in its __array_ufunc__ implementation.
Suggested Fix
if (errval) {
goto fail; // cleanup path that DECREFs full_args
}Environment
- NumPy version: current main
- Affected:
np.add.reduce(),np.accumulate()etc. with__array_ufunc__overrides that raise
Activity
Vatmuri2 commentedon Jun 19, 2026
Saw this is marked low priority. I was looking for a good first contribution and I'd love to take this one if it's still up for grabs!
My plan: the one-line goto fail fix, plus a regression test that checks the operand's refcount stays flat when array_ufunc raises during a reduce. I'll get a PR up soon. Totally happy to adjust the plan, would love to learn from this, let me know if there's any other considerations!
[-][BUG] Reference leak in PyUFunc_GenericReduction on CheckOverride error[/-][+]BUG: Reference leak in PyUFunc_GenericReduction on CheckOverride error[/+]